1. Field Of The Invention
This invention relates to a conveyor control apparatus in a fully automatic labeling system wherein commodities are successively sent in to have their weights measured and wherein labels, are automatically attached, which contain printed data corresponding to the measured values.
2. Description of the Prior Art
In general, fully automatic labeling system of this type comprises a sending-in conveyor which sends a commodity in, a weighing conveyor which measures the weight of the commodity, and a sticking conveyor on which data based on the measured value is printed on the commodity, the respective conveyors having their operations controlled independently. Accordingly the commodity is sent in in coordination with the timing of the operations of weighing and labeling. The prior-art system, however, has for its principal purpose to merely transport the commodity smoothly and is not suited to an actual situation in which the supply of the commodity ceases. More specifically, even when the supply of the commodity has ceased, the weighing conveyor and the sticking conveyor continue to operate, thus allowing the system to run at idle which results in problems with an increase in power dissipation and a reduced lifetime of the system decreases. The operation control itself of each conveyor is affected by the combination of a sensor for detecting the commodity and a timer. The time set on the timer changes greatly depending upon external conditions such as temperature changes. Furthermore, the exactness of the weighing and the safety of the control of the conveyor operation is uncertain. The operation control functions to signify that two commodities are placed on the weighing conveyor or that an interval arises between the sequence of transportation timings. There is the contradiction that when accuracy increases, the efficiency is decreased because of the amount of time necessary to increase accuracy, whereas when the efficiency is enhanced, accuracy is sacrificed. Also in the full-auto labeling system, a print fixing operation in which the print content is fixed is sometimes carried out. In this case, the conveyors form a mere transportation passage, and it is difficult to reliably perform the commodity transportation conforming with the label issuing timing.
Further, when there is a large quantity information to be printed on a label therefore it cannot be printed with the one-stage print, and hence, a two-stage print must be performed. In case of the two-stage print, the printing time naturally becomes long, and the commodity transportation interval is set in compliance with the timing of the two-stage print in the prior-art system. Therefore, the efficiency becomes very low when the one-stage print is adopted. In order to raise the efficiency, a circuit is necessary which is separately operated by change-over from a one-stage print to a two-stage print.